Redaction Leak Detector - Free Online Browser Tool

Audit documents for searchable text hidden beneath opaque shapes, blackouts, or redaction rectangles, and safely scrub detected leaks.

Drawing a black rectangle over sensitive text does not redact it: the characters remain in the PDF text layer, ready to be copied, selected, or extracted by automated scrapers. The Redaction Leak Detector inspects vector shapes, drawing operator paths, and redaction annotations, detects intersecting live text streams, and provides an instant audit report alongside a permanent image-rasterised remediation pass.

This redaction leak detector utility runs completely inside your web browser. Your document is opened locally and processed on your own device using JavaScript and WebAssembly, so your file is never uploaded to any server. There is no signup, no watermark and no limit on how many documents you can handle.

  • 100% client-side - files never leave your device
  • Instant processing, no upload wait
  • Works on desktop, tablet and mobile
  • Free forever, no account required

Common next steps: Bulk Keyword Redaction, Sanitise PDF for Sharing, Sanitize Tracking IDs, Inspect Security & Permissions.

How to Use the Redaction Leak Detector Tool

Four steps, and the whole thing runs locally on your own device.

  1. Upload the redacted PDF

    Choose or drop the document you want to verify before public disclosure or external transmission.

  2. Select action and remediation

    Run an audit report only, or automatically scrub detected leaks using permanent rasterisation.

  3. Audit and inspect results

    Review identified overlay boxes and exposed underlying text fragments in the audit report.

  4. Download the secured PDF

    Receive your clean, sanitized document with no hidden or recoverable text traces.

Frequently Asked Questions

How does text leak through black redaction boxes?

In many PDF editors, drawing a black box simply places a colored rectangle above the text stream. The visual appearance changes, but the underlying text operators remain intact and searchable.

What does the detector check?

It evaluates path construction operators, rectangle geometries, and PDF annotation bounds (Square, Redact, Polygon), comparing their 2D bounding boxes against the text glyph coordinates.

How does scrubbing remove the leak permanently?

Permanent rasterisation re-renders the affected pages into a flat bitmap image at high resolution (150–300 DPI). The text stream is completely replaced, making extraction impossible.

Does this tool detect whiteout rectangles as well as black boxes?

Yes. It checks vector fill colors, stroke paths, and annotation rectangles of any color, identifying any drawn shape that covers underlying text.

Are my confidential documents uploaded to any server?

No. All parsing, leak detection, and remediation happen entirely within your local browser sandbox.